Signal appliance for telephone-switchboards.



Patented July 3|, I900. F. R. MGBERTY &. J. L. MGHUABRIE.

SIGNAL APPLIANCE FOR TELEPHONE SWITGHBOARDS.

(Application filed Nov. 22, 1897.)

(No Model.)

Witnesses:

V I nvento rs A 7/0 M$1JVEZE1W&$MSM9QW I by their Attys PATENT-- OFFICE, I

FRANK R. MCBERTYJOF DOWNERS GROVE, AND JAMES L. MOQUARRIE, OF CHICAGO, ILLINOIS, ASSIGNORS TO THE WESTERN ELECTRIC COMPANY,

or CHICAGO, mun OIS.

SIGNAL APPLIANCE FOR TELEPHONE-SWITCHBOARDS.

SPECIFICATIGN forming part of Letters Patent No. 654,749, dated July 31, 1900. Application filed November 22, 1897- Serial No. 659,493. (No model.)

To aZZ whom it may concern: I

Be it known that we, FRANK R. MCBERTY, residing at Downers Grove, inthe county of Du Page, and JAMES L. MCQUARRIE, residing at Chicago, in the county of Cook, State of Illinois, citizens of the United States, have invented a certain new and useful Improvement in Calling and Signaling'Appliances for Telephone-Switchboards, (Case No. 56-4,) [0 of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawing, forming a part of this specification.

This invention concerns the calling apparatus for an operator in a telephone-switchboard and means for permitting her to supervise established connections.

This object of the invention is to facilitate the operators work of transmitting calls to subscribers stations and of determining the subscribers response to such calls and to employ therefor apparatus cheaper and more simple than has heretofore been provided. I In a certain type of switchboard used with z 5 lines provided with means for producing cur-' rent in the lines during the use of the telephones supervisory signals have been asso-' ciated with each plug-circuit or link conductor for uniting lines, responsive to current in the lines, and designed to indicate to the attendant in charge of them the condition of use or disuse of the substation appliances. The signal associated with the calling plug, Which is used in making connection with the line called for, serves primarily to show the operator when the subscriber at the station called has responded to the signal, and failure to respond promptly calling for a second signal. The present invention aims to dispense with the supervisory signals associated with each pair of plugs and to use in place of them a single clearing-out signal for each plug-circuit, together with a general supervisory signal for an operators entire equipment of plug-circuits, a key for bringing this signal and the calling generator simultaneously into connection with any desired calling plug, and means for preventing the transmission of the call-signal in the event of the subscriber having responded to the first call.

In operating this mechanism it is designed that the attendant, having established connection with several lines, shall depress the key associated with each of the calling plugs after a short interval from the completion of the connection, whereupon if the subscriber has not responded to the call first sent a second calling current will be transmitted to the substation, or if he has responded the generator of calling current will be automatically disconnected from the calling plug and the general supervisory signal will indicate the fact of his response to the operator.

To this end the invention consists in the combination, with several calling plugs and their respective plug-circuits, of a calling key for each plug, a generator of calling current, a relay, and a general supervisory signal, any calling key being adapted to connect the generator of current and the relay witha called line with which the corresponding plug is connected, the relay being adapted to respond to current of special character through the line determined by the position of use of the subscribers telephone and serving in its response to disconnect the generator of calling current from the calling plug and to cause the display of the general supervisory signal. Either of the two functions of the relay before mentioned may be solely employed-that is, the relaymay serve merely to control a I general supervisory signal to show the operator, upon the depression of a special key, that the called subscriber has responded, or it may serve only to disconnect the calling generator in the event of the subscribers response; but inasmuch as the complete appliance as generally described is of much more efficient as sistance to the operator than the relay would be used in but one of its functions we prefer to describe the. complete mechanism.

The invention is illustrated in the attached drawing, which represents two substations connected by telephone lines with a switchboard in the central office, together with a 5 pair of connecting-plugs for uniting lines in' the switchboard, the plug-circuit beingprovided with our improved supervising and calling appliances.

Receiving-telephones a and transmittingtoo telephones a, call-bells a and telephone-- line conductors 1 and 2 lead from these appliances at each substation to a spring-jack b and thence through an individual signal cto the poles of a batteryd in the central office. The spring-jack is adapted-to break the connection of the line-signal with the line when a plug is inserted in the jack. Apair of plugs c and e are shown forjuniting lines into a" complete circuit by means of thespring-jacks Like contact;pieces of the two of the lines. plugs are united by conductors 3 and 4', which constitute the system of conductors which we designate the plug-circuit. The plug e is designed to be used in making connection with calling lines, While plug 6 is reserved I for n'sein makingtconnection therefrom toa line called for. v It will beunderstood thata large'number of telephone-lines are grouped in'the switch- '1 board before each operator and that each operator is furnished with a considerable number of pairs of plugs, with their plug-circuits and associated appliances.

Conductors 5 and-6 lead from wires 3 and 4 of the plug-circuit to the poles of the battery d or other suitable source of current. These conductors include the magnet-Windings of a clearing-out signal f. These windingsshould be characterized by great impedance in order that the shunting of telephonic current through the bridge-circuit. formed by wires 5 6 may be prevented. The switch-contacts of a calling key g are interposed in'the conductors 3 and 4 of the plugcircuit; The normal resting anvils of the switch-springs of this key form the terminals of the portions of conductors 3 and 4 going to the plug e, so that the separation, of the switch-springs from their resting anvils.

breaks the continuity of the plug-circuit. The alternate contact anvils of these switchsprings form the terminals of a generator h of. calling current. This generator may give an alternating current of usual character as employed for ringing bells of telephone-sub stations. The magnet-winding of a relay&' is included in the circuit '7 of the generator. This relay should be so adjusted that the currentfinding circuit from the generator over a telephone-line and through the condenser and high-resistance bell at the station thereof will be insufficient to draw-up the armature, butthat the current through the telephones, which are of comparatively-low resistance, should cause the attraction of the armature. This armature, with its normal resting contact, controls the continuity of the circuit 7, including thecalling-generator,.being adapted to break the circuit between the generator and the conductor'3 of the plugorator.

circuit when the armature is drawn toward the magnet, the portion of wire 7 extending to conductor 3 being for this purpose connected with the resting anvil '6 of the armature-lever i and the other of the severed terminals of the Wire being connected with the armature-lever. The forward contact i of the armature-lever forms the terminal of a wire 8, leading to 'the wire 7 at a point between the' conductor lot the plug-circuit and the generator. The continuity of this wire 8 is controlled by auxiliary switch-contacts g and 9 connected with the key g, which become closed together in the use of the key for calling. When the armature 2' is drawn against this forward contact-piece, there is in effect a local circuit of the generator h made up of portions of wire 7 and the wire 8,

including the magnet 'i, the switch-contacts 2' i the switch-contacts g, g of the key, and the general supervisory signal It; The'signal k may be an incandescent lamp and should be of such character as to become illuminated with the current flowing in this closed local circuit.

Each plug-circuit of an operators equipment' is to be furnished with a clearing-out signalfand with a calling. key 9. There is to be but one source OfCIII'IGDll h, one relay 1, and one general supervisory signal 7c for each. group of plug-circuits, however. The normally-open terminals of thewires 7 and 8 will extend to the contact-pieces of the different keys gin multiple, asindicatedby the short lines emanating from. the wires, in a manner which will be apparent to those versed in the construction'of telephone-switchboards.

The subscriber at station A, for example,

may call for connection with another line by removin g his telephone from its switch,.whereupon current-will flow from battery cl through the signal 0 and the closed circuit'at the substation, bringing aboutthe display of the signal, and thus calling the attention of the-op- Complying with the signal, the operator will insert plug e into the spring-jack b of the calling line, at the same time bring- 1 ing her telephone into connection with the plug-circuit to learn the subscribers order.

Having received his instruction, she will insert plug 3' into the spring-jactb of the line called forand will depress the plunger of the calling key 9 to thrust the switch-springs thereof against the terminals of the generator-circuit, and thus to'ring the bell at the station to be signaled. Inasmuch as the circuit at the called station is completed'only through the high-resistance bell and the condenser there, the current through relayi will be insuflicient to operate that relayand the.

generator will be permitted to 'perform its function. Having transmitted a call-signal of momentary duration, the operator may release the key g and attend to other work. After a short interval she should return to the connection thus established and again depressthe key 9. If the subscriber called for has not yet responded, the current from generator h will flow as in the initial call, being insufficient to work the relay 1', and the bell at the substation will be rung a second time. If, however, the subscriber has answered the first call and removed his telephone for use, the increased current permitted to flow through relay c' in virtue of the diminished resistance of the circuit at the substation will excite the relay and draw its armature forward. The movement of this armature will break the'circuit 7 to the plug-circuit between the eontact-pieces 11 and 2' and thus will instantly cut off the calling current, so

as to avoid'annoying the subscriber. In its further movement it will close upon contact-piece 2' completing the local circuit, including the generator, the magnet, and the general supervisory signal 7c, whereby the operator will be informed as to the condition, of the apparatus at the called station. On noting the indication of this signal she will release the key 9 and give no further attention to the united lines. 7

In practice it is found that an operator has ample leisure for manipulating keys while attending to calls by means of her telephone. Hence in the employment of the apparatus herein described she may easily depress the key g of a plug recently inserted in a line, whereby a tardy subscriber will be signaled a second time or the prompt response of the subscriber will be indicated. vision which is substantially identical in character with that furnished by special supervisory signals, one for each plug-circuit, is provided by our improved mechanism with great economy of apparatus.

Various changes in the arrangement of parts and the nature of the instruments employed may be made without departing from the spirit of our invention.

The invention is defined in the following claims.

We claim- 1. The combination with telephone-lines and plugs and plug-circuits for making connection therewith, each telephone-line being provided with a switch atits station for changing the resistance of the line-circuit in the use of the telephone, of a key in each plugcircuit, a general supervisory signal and a source of current, each key being adapted to connect the general signal and source of current temporarily with the corresponding plugcircuit to determine the condition of use or disuse of the substation instruments, as described.

2. The combination with telephone-lines, each provided at its station with a switch for changing the resistance of the line in response to a call-signal, of calling plugs and plug-circuits therefor for making connection with the line, a supervisory signal and a source of current, a key in the plug-circuit and circuit connections of the key and su- Thus a super- 'pervisory signal, whereby the signal and the source of current may be temporarily connected with a plug-circuit to determine the condition of the appliances at the substation, as described.

3. The combination with telephone-lines,

each provided at its station with means for the plug-circuit and to complete it with the said general supervisory signal and source of current, as described.

4. The combination with telephone-lines, each provided at its station with a telephoneswitch adapted to change the resistance of the line in the use of the telephone, pairs of plugs and plug-circuits therefor, a source of current and a clearing-out signal connected'with each pair of plugs, a general supervisory signal for the group of plugs, and a key in each plug-circuit, each key being adapted to break the connection between the plugs and to connect one of them in circuit with the said general supervisory signal, whereby an operator may determine the condition of use or disuse of the telephone at a substation, as de scribed.

5. The combination with telephone-lines, each provided at its substation with a callbell in a closed bridge of high resistance, a bridge of low resistance, and a switch for closing the bridge of low resistance, of plugs and their plug-circuits for making connection with the lines, a single generator of calling current for the group of plugs, an electromagnetic switch for the group of plugs, a key for each plug in the plugcircuit thereof adapted to connect the generator of signaling current and the magnet of the electromagnetic switch with the corresponding plug, the electromagnetic switch being adapted to respond to current produced in the line when the'said low-resistance bridge thereof is closed, the switch-contacts of the switch being interposed in the circuit of the generator to break the circuit when'the magnet so responds, as described.

6. The combination with telephone-lines, each provided at its station with a signal-receiving instrument and a switch adapted to change the circuits of the line inresponse to a call, of plugs and plug-circuits therefor to make connection with the lines, a generator of signaling-current and an electromagnetic switch for the group of plugs, a key for each plug in the plug-circuit thereof adapted to connect the source of signaling-current and the magnet of said switch with the corresponding plug, the switch being adapted to operate by current in the line produced through the agency of said circuit connections as changed ICC 4 I o I 654,749

by the switch, said switch controlling the a plication of current of the generator to the line, as described.

7. The combination with telephone-lines,

each provided at its substation with a callbell and a switch for changing the circuit connections of the line in response to a call,

of plugs and-plug-circuits for making connection with the lines, asource of calling current, an electromagnetic switch, and a general superv-isory signal, a key associated with each plug adapted to connect the electromagnetic switch, together with a source of current, to

the line, said electromagnetic switch being adapted to respond to current determined by the condition of the line-circuit at the substation" as changed by said switch, said switch being adapted to connect the generator of callingcurrent with the line in one position and to cause the display of the supervisory signal in its other position; whereby the depression of a calling key will result in the transmission of a-call-signahfor in the display of said supervisory signal, according to the position of the said switch. at the substation, as described.

the relay being responsive to current through the low-resistance bridge-at the station of the line and having its switch-contacts interposed in the calling circuit tointerrupt the calling current in its response, and ageneral supervisory signal controlled by the relay, substantially as described.

In witness whereof we hereunto subscribe our names this 29th day of September, A. D.

FRANK R. MOBERTY. JAMES L. MOQUARRIE.

Witnesses: v

ELLA EDLER, DUNCAN E. WILLETT. 

